In 3D X-ray imaging, a sequence of two-dimensional projection images which have been acquired from different recording directions in relation to the object to be recorded is converted into a 3D representation of the object density by means of a tomosynthesis or CT algorithm. The achievable image quality of the 3D image is dependent to a significant degree on the type of data acquisition, in particular on the recording directions from which the projection images were recorded and on the associated recording times. In the prior art the different recording directions are generally arrived at by means of a mechanical movement of the recording system (medical C-arm, CT scanner). This means that the recording trajectory (the track through all recording positions) is traversed sequentially. Problems with this method are, for example, that movements during the recording create artifacts, and that a useful reconstruction is available only after the recording trajectory has been terminated completely.
The problem of cardiac movements is dealt with by means of ECG gating, for example, though this leads in some cases to extended recording times, since the movement of the X-ray source cannot be stopped during the unwanted cardiac phases. Moreover, mechanical movements can be replaced by innovative multi-pixel X-ray sources which in principle allow any desired switching of the X-ray focus.